I don't understand the rationale for this fix. You are saying that the dead
branch is not dce'd, and lno does not like it. So, why not fix dce? A dead
branch is dead branch, why this workaround?
Sun
On Wed, Dec 14, 2011 at 12:34 PM, Gang Yu <yugang...@gmail.com> wrote:
> Hi,
>
> Would a gatekeeper please help review the fix for bug934 , regression
> caused by r3843?
>
> segment-fault function snippet of bug case:
>
> void LibRaw:: tiff_set (ushort *ntag,
> ushort tag, ushort type, int count, int val)
> {
> struct tiff_tag *tt;
> int c;
> if (type < 3 && count <= 4)
> for (c=0; c < 4; c++) tt->val.c[c] = val >> (c << 3);
> }
> void LibRaw:: tiff_head (struct tiff_hdr *th, int full)
> {
> if (full) {
> tiff_set (&th->ngps, 3, 2, 2, (imgdata.other.gpsdata)[30]);
> tiff_set (&th->ngps, 4, 5, 3, ((char *)(&(th->gps[6])) - (char *)th));
> tiff_set (&th->ngps, 5, 1, 1, (imgdata.other.gpsdata)[31]);
> }
> int c, row, col, soff, rstep, cstep;
> for (row=0; row < (imgdata.sizes.height); row++, soff += rstep) {
> }
> }
>
> at O3 , tiff_set is inlined into tiff_set, at PREOPT_LNO_PHASE,
> expression
> if (type <3 && count <=4), i.e, whirl expression
>
> U4U2LDID 0 <st 89> T<7,.predef_U2,2>
> U4INTCONST 2 (0x2)
> U4U4LE
> I4I4LDID 0 <st 90> T<4,.predef_I4,4>
> I4INTCONST 4 (0x4)
> U4I4LE
> I4CAND
> U4I4CVT
> after codemap, is transfered to
> > LDC U4 1 <u=2 cr19> flags:0x0 b=-1
> > U4I4CVT <u=2 cr33> isop_flags:0xc0000 flags:0x1 b=-1
> >OPR_FALSEBR 6914 b=-1 flags:0x2 pj2 Sid-1
> DCE does not delete the unreachable branch under this condition, which
> then emits back to H whirl
> as
> IF {line: 1/131}
> U4INTCONST 1 (0x1)
> THEN
> ...
> ELSE
> BLOCK
> END_BLOCK
> END_IF
>
> this will make proactive transformation phase in PREOPT_LNO1_PHASE
> uncomfort, then it asserts.
>
> Suggested patch, keep the orginal handling of U4I4CVT const , only change
> under the MAINOPT_phase.
>
>
> osprey/be/opt/opt_htable.cxx -- 148c4e2..6499b99 100644
> --- a/osprey/be/opt/opt_htable.cxx
> +++ b/osprey/be/opt/opt_htable.cxx
> @@ -2273,7 +2273,9 @@ CODEMAP::Canon_cvt(WN *wn,
> Get_mtype_class(OPCODE_desc(op))) != 0 &&
> MTYPE_size_min(OPCODE_rtype(op)) == MTYPE_size_min(OPCODE_desc(op))
> &&
> // bug912 open64.net. Do not delete U4I4CVT if his kid is a
> constant
> - (!(OPCODE_rtype(op) == MTYPE_U4 &&
> + // bug934 open64.net. Only do this at MAINOPT_PHASE.
> + (!(_phase == MAINOPT_PHASE &&
> + OPCODE_rtype(op) == MTYPE_U4 &&
> OPCODE_desc(op) == MTYPE_I4 &&
> ccr->Tree() == NULL)))
> return propagated;
>
> Would a gatekeeper help a review?
>
> BTW, thanks for Xiaojing for report the bug.
>
> Regards
> Gang
>
>
> ------------------------------------------------------------------------------
> Cloud Computing - Latest Buzzword or a Glimpse of the Future?
> This paper surveys cloud computing today: What are the benefits?
> Why are businesses embracing it? What are its payoffs and pitfalls?
> http://www.accelacomm.com/jaw/sdnl/114/51425149/
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>
------------------------------------------------------------------------------
Cloud Computing - Latest Buzzword or a Glimpse of the Future?
This paper surveys cloud computing today: What are the benefits?
Why are businesses embracing it? What are its payoffs and pitfalls?
http://www.accelacomm.com/jaw/sdnl/114/51425149/
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